Solid phase synthesis of organic molecules is the method of choice for preparation of libraries and compound megaarrays, which are currently being applied for screening in the quest to find new drugs or pharmaceutical lead compounds, i.e., compounds which exhibit a particular biological activity of pharmaceutical interest, and which can serve as a starting point for the selection and synthesis of a drug compound, which in addition to the particular biological activity of interest has pharmacologic and toxicologic properties suitable for administration to animals, including humans.
Fluorous synthesis is in its principle similar to solid phase synthesis. In fluorous synthesis the certain component of the reaction (starting material, reagent, or product) is preferentially retained in the fluorine atoms containing phase due to its high content of fluorine atoms. Fluorous phase is usually the high density one and therefore it can be separated as the lower phase in the multiphase system. Manual synthesis requires repetitions of several relatively simple operations of addition of reagents, incubation and separation of liquid phases. This character of the synthetic process renders it optimal for automation.
Several designs of automated instruments for combinatorial synthesis utilizing solid phase synthesis have appeared in the patent and non-patent literature. However, there is no instrument designed for the fluorous synthesis, since the simple principle of separation of phases by filtration is not applicable.
The productivity of automated instruments can be dramatically improved by use of disposable reaction vessels (such as multititer plates or test tube arrays) into which reagents are added by pipetting, or by direct delivery from storage containers. The optimal storage vehicle is a syringe-like apparatus of a material inert to the chemical reactants, etc., e.g., a glass syringe, allowing the storage of the solution without any exposure to the atmosphere, and capable of serving as a delivery mechanism at the same time. See U.S. Pat. No. 6,045,755. An alternative technique based on the removal of upper layer of liquid by suction from the surface above the separated layers is limited to the arrays of up to a hundred of suction needles. (For similar situation in solid phase synthesis see U.S. Pat. No. 6,045,755). The present application is an improvement upon U.S. Pat. Nos. 5,202,418, 5,338,831, 5,342,585, and 6,045,755 which describe placement of resin in polypropylene mesh packets and removal of liquid through the openings of these packets, or removal of the liquid from the pieces of porous textile-like material by centrifugation, or removal of liquid phase from the solid phase by centrifugation of tilted plates. Liquid removal by centrifugation was described and is the subject of several publications (see the book “Aspects of the Merrifield Peptide Synthesis” by Christian Birr in the series Reactivity and Structure Concepts in Organic Chemistry vol. 8, K. Hafner, J.-M. Lehn, C. W. Rees, P. von Rague, Schleyer, B. M. Trost, R. Zahradnik, Eds., Sringer-Verlag, Berlin, Heidelberg, N.Y., 1978, and German Patent Application P 20 17351.7, G. 70 13256.8, 1970. These references describe the use of centrifugation for liquid removal from slurry of solid phase particles in a concentrical vessel equipped with a filtration material in its perimeter and spun around its axis. See also WO99/25470, hereby expressly incorporated by reference in its entirety.
None of the prior art contemplates the separation of two (or more) immiscible, or partially miscible liquids of different density by removal of lighter layers of liquids by creation of “pockets” from which material cannot be removed by centrifugal force. This technique can be used in situations where multiplicity of products are to be extracted in parallel (e.g. in parallel purification of products of combinatorial synthesis). However, there is a need for a simple, efficient means of separating liquid phases during fluorous phase synthesis of organic molecules, particularly a method amenable to use with automated methods for such syntheses.
Furthermore, complete removal of the liquid from the multiplicity of vessels by spinning the array of wells attached with “reverse tilt” (tilting away from the axis of rotation) can find its application in biological assays where fast repeated washings of surface bound reagents or cells are required, and in applications where synthesis is done directly on the surface of the reaction vessels.